题目内容
在平面直角坐标系
中,设定点
,
是函数
图象上一动点. 若点
,
之间的最短距离为
,则满足条件的实数
的所有值为
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557903413.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557919515.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557934289.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557950697.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557934289.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557981300.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557997386.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558012283.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558028223.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558044363.png)
依题意,定点
在直线
上,直线
与曲线
的交点
,
,由两点间的距离公式得这两点间的距离为
,∴
满足条件.
设![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558168642.png)
,则![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240155582001063.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558215958.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240155582311224.png)
设
,∵
,∴
,
,
即
,解得
,而
,∴
.
故满足条件的实数
的所有值为
,![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558044363.png)
【考点定位】考查函数
与
的图象性质,两点间的距离公式,考查不等式的性质、二次函数的最值. 较难题.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557919515.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558075402.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558075402.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558106463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558122430.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558122386.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015557997386.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558153346.png)
设
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558168642.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558184553.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240155582001063.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558215958.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240155582311224.png)
设
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558246569.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558262454.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558278410.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/201408240155582931562.png)
即
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558324612.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558340485.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558340398.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558356448.png)
故满足条件的实数
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558012283.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558028223.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558044363.png)
【考点定位】考查函数
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558106463.png)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140824/20140824015558075402.png)
![](http://thumb.zyjl.cn/images/loading.gif)
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